Principles of Instrumental Analysis, 6th Edition
6th Edition
ISBN: 9788131525579
Author: Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Publisher: Cenage Learning
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Question
Chapter 25, Problem 25.12QAP
Interpretation Introduction
(a)
Interpretation:
The slope, intercept, regression statistics including the standard deviation about regression should be calculated.
Concept introduction:
Concentration Dopamine take as the dependent variable and Peak current take as the independent viable.
Concentration of Dopamine take to y axis and Peak current take to x axis.
Interpretation Introduction
(b)
Interpretation:
The concentration of dopamine at peak current 2.92 nA should be calculated using the plotted graph.
Concept introduction:
The graph is plotted by taking dopamine concentration as dependant variable and peak current as independent variable.
Therefore, for the given peak current can find the dopamine concentration using the trend line equation.
Interpretation Introduction
(c)
Interpretation:
Standard deviation of the unknown concentration should be calculated.
Concept introduction:
Standard deviation will give that the deviation of the value from the average.
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(a
4 shows scanning electron microscope (SEM) images of extruded
actions of packing bed for two capillary columns of different diameters,
al 750 (bottom image) and b) 30-μm-i.d. Both columns are packed with the
same stationary phase, spherical particles with 1-um diameter.
A) When the columns were prepared, the figure shows that the column with
the larger diameter has more packing irregularities. Explain this observation.
B) Predict what affect this should have on band broadening and discuss your
prediction using the van Deemter terms.
C) Does this figure support your explanations in application question 33?
Explain why or why not and make any changes in your answers in light of
this figure.
Figure 4 SEM images of
sections of packed columns
for a) 750 and b) 30-um-i.d.
capillary columns.³
fcrip
= ↓ bandwidth Il temp
32. What impact (increase, decrease, or no change) does each of the following conditions have on the individual
components of the van Deemter equation and consequently, band broadening?
Increase temperature
Longer column
Using a gas mobile phase
instead of liquid
Smaller particle stationary phase
Multiple Paths
Diffusion
Mass Transfer
34. Figure 3 shows Van Deemter plots for a solute molecule using different column inner diameters (i.d.).
A) Predict whether decreasing the column inner diameters increase or decrease bandwidth.
B) Predict which van Deemter equation coefficient (A, B, or C) has the greatest effect on increasing or
decreasing bandwidth as a function of i.d. and justify your answer.
Figure 3 Van Deemter plots for hydroquinone using different column inner diameters (i.d. in μm). The data was
obtained from liquid chromatography experiments using fused-silica capillary columns packed with 1.0-μm particles.
35
20
H(um)
큰 20
15
90
0+
1500
100
75
550
01
02
594
05
μ(cm/sec)
30
15
10
Chapter 25 Solutions
Principles of Instrumental Analysis, 6th Edition
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